<div class="stair">
  <div class="cube">
    <div class="face cube__front"></div>
    <div class="face cube__back"></div>
    <div class="face cube__right"></div>
    <div class="face cube__left"></div>
    <div class="face cube__top"></div>
    <div class="face cube__bottom"></div>
  </div>
  <div class="cube">
    <div class="face cube__front"></div>
    <div class="face cube__back"></div>
    <div class="face cube__right"></div>
    <div class="face cube__left"></div>
    <div class="face cube__top"></div>
    <div class="face cube__bottom"></div>
  </div>
  <div class="cube">
    <div class="face cube__front"></div>
    <div class="face cube__back"></div>
    <div class="face cube__right"></div>
    <div class="face cube__left"></div>
    <div class="face cube__top"></div>
    <div class="face cube__bottom"></div>
  </div>
  <div class="cube">
    <div class="face cube__front"></div>
    <div class="face cube__back"></div>
    <div class="face cube__right"></div>
    <div class="face cube__left"></div>
    <div class="face cube__top"></div>
    <div class="face cube__bottom"></div>
  </div>
  <div class="cube">
    <div class="face cube__front"></div>
    <div class="face cube__back"></div>
    <div class="face cube__right"></div>
    <div class="face cube__left"></div>
    <div class="face cube__top"></div>
    <div class="face cube__bottom"></div>
  </div>
  <div class="cube">
    <div class="face cube__front"></div>
    <div class="face cube__back"></div>
    <div class="face cube__right"></div>
    <div class="face cube__left"></div>
    <div class="face cube__top"></div>
    <div class="face cube__bottom"></div>
  </div>
  <div class="cube">
    <div class="face cube__front"></div>
    <div class="face cube__back"></div>
    <div class="face cube__right"></div>
    <div class="face cube__left"></div>
    <div class="face cube__top"></div>
    <div class="face cube__bottom"></div>
  </div>
</div>